What Randomness Exists

What Randomness Exists

The engine is deliberately split: some dice are load-bearing and some were removed. Knowing which is which keeps a well-meant cleanup from sterilising a world.

Where dice are rolled

Birth orientation. A child faces a random direction, gated by rotationEnabled. For a rooted producer this is the only spatial exploration available — it cannot move, so the direction it faces is the only thing that varies between its offspring. Remove it and a lineage becomes a single orientation forever.

Mutation. Which cell changes, what it becomes, whether the rate itself drifts up or down, and every per-weight perturbation of the brain.

Sense channel 11. Fresh noise every tick, fed to the brain as an input. This is the one place a creature can get randomness into its decisions, and only if evolution wires Win to that channel. It is an opportunity, not an imposition.

World generation. Founder placement and founder bodies, when a world starts with the diverse random crowd. The default single ancestor is deterministic: a fixed body at the centre of the grid.

Where no dice are rolled

Movement. A creature decides, and the decision stands. If the move is blocked it simply fails; nothing jolts the creature to a random heading, and there is no timer that overrides a deliberate hold.

Measured on 10,000 decisions: zero RNG draws inside the movement path, and two runs from the same state produce bit-identical trajectories.

Why movement has no safety net

The engine previously rescued stuck organisms: on a blocked move or a move_range timeout it would rotate them randomly. That fired on 33.3% of all decisions — a third of every creature's behaviour was dice rather than brain, and the network never experienced the consequence of walking into a wall, only a random jump.

That rescue made sense for a stateless lookup-table brain, which could lock onto an obstacle forever with no way to represent "I tried this already." A recurrent network has memory, plus halt, reverse and two turn actions. Escaping is its own job now, and a lineage whose brains cannot manage it is meant to die.

The practical consequence: early generations are more fragile than they were. That is the selection pressure working, not a defect.

Reproducibility

Movement is deterministic, but a whole world is not reproducible from a seed today — the RNG is global and shared, so anything that changes the order or number of draws (a birth, a death, a mutation) shifts the stream for everything after it. Comparing two runs means fixing the seed and the sequence of events.